(3868) Mendoza

J. Oey, Leura Observatory, Leura, N.S.W., Australia; P. Pravec, P. Kusnirak, and K. Hornoch, Ondrejov Observatory; J. Brinsfield, Via Capote Observatory, Thousand Oaks, CA, U.S.A.; V. Chiorny, Kharkiv Observatory; D. Pray, Carbuncle Observatory, W. Brookfield, MA, U.S.A.; and M. Pikler and M. Husarik, Skalnate Pleso Observatory, report that photometric observations obtained during Apr. 25 to May 25 reveal that minor planet (3868) is a binary system with an orbital period of 24.38 hr. The primary shows a period of 2.77090 +/- 0.00005 hr and has a lightcurve amplitude of 0.10 mag, suggesting a nearly spheroidal shape. Mutual eclipse/occultation events with a depth of 0.05 mag indicate a secondary-to-primary mean-diameter ratio of 0.22 +/- 0.02. The mean absolute R-band magnitude and the slope parameter of the system are H_R = 12.30 +/- 0.04 and G_R = 0.23 +/- 0.05.